3 forms of Irony

Verbal Irony- The title itself is a form of verbal irony, as the guest is actually a prisoner.

Dramatic Irony- Daru believes he hasn't made a choice and isn't responsible for what will ultimately happen to the Arab. He doesn't want to be involved, and he is of the belief that if he doesn't make the choice between turning the Arab in or letting him go he's able to claim neutrality. Ironically, his decision is to give the Arab food and money, something that only prolongs the Arab's delay in turning himself in.

Lastly, Balducci in considered the story's antagonist simply because his behavior toward Daru and the Arab is rude.